Colleen Cumming and his studio “An Exploration of Mandibular Metrics in the Population of Sanisera”

Colleen Cummings in one of the laboratories of the Sanisera Field school

The necropolis of Sanisera, dating from the 4th to 6th centuries CE provides an opportunity to examine the physical characteristics of the people from this site. For this pilot study, only mandibles were used for analysis as there were mandibles available on hand from both Necropolis 6 and Necropolis 4. As a staunch bone, the mandible survives fairly well in this population, even in situations where the cranium might be highly fragmented. By doing so it is hoped that we can determine whether the population was homogenous or a mixed group, and through comparisons to Menorcan sites from different time periods as well as other sites around the Mediterranean, identify the ancestry of these people. In order to do this, metric and non-metric traits of the cranial and post cranial skeletons will need to be analyzed. There were 15 mandibles from Necropolis 6 available for analysis and 12 from Necropolis 4. Each of these were measured and assessed for non-metric traits according to the guidelines presented in Standards for Data Collection from Human Skeletal Remains (Buikstra & Ubelaker 1994: 78, 91).

Two distinct jaw shapes emerged in the course of this pilot project. The first of these has a sharp angle at the gonion, and the second has a much more sloped shape, the gonion blending into the mandibular body. The incidence of non metric traits in this population was fairly low, and was represented only by accessory mental foramina in two individuals of the 27 studied (7%).

From such a small sample size and in the absence of statistical testing, it is difficult to make any grand conclusions about the mandibular structures at this site, except to say that aside from the visual determination of some different mandibular shapes, there does not seem to be a great deal of clearly definable intra site variation in mandibular size. This would suggest that we have here a fairly homogenous population, or at least one that is mixed enough to blur any potential distinctions between groups.

Mandible from the Sanisera Field school

There is some potential for sexual dimorphism in mandible size, which is not unexpected given that males and females typically do exhibit differences in mandibular size and shape. When the mandibular measurements from the Sanisera population are compared to those from other sites and time periods throughout the world though, it is clear that as a whole, the mandibles at Sanisera are relatively small in size. This is an interesting result, as given the time period and the likely diet of the people living at this site, it suggests a genetic component to the small jaw size.